WASHINGTON » As the government shutdown dragged on, Sen. Susan Collins of Maine was spending another weekend on Capitol Hill, staring at C-SPAN on her Senate office television as one colleague after another came to the floor to rail about the shuttered government.

Frustrated with the lack of progress, Collins, a Republican, two Saturdays ago quickly zipped out a three-point plan that she thought both parties could live with, marched to the Senate floor and dared her colleagues to come up with something better. A few days later, two other Republican female senators eagerly signed on – Lisa Murkowski of Alaska, who overcame the Tea Party to win re-election in 2010, and Kelly Ayotte of New Hampshire, who benefited from the Tea Party wave.

Together the three women started a bipartisan group whose negotiating framework formed the centerpiece of a tentative Senate deal nearing completion Monday to reopen the federal government and avert a disastrous default.

"Before I went to the Senate floor, no one was presenting any way out," Collins said. "I think what our group did was pave the way, and I’m really happy about that."

In a Senate still dominated by men, women on both sides of the partisan divide proved to be the driving forces that shaped a negotiated settlement. The three Republican women put aside threats from the right to advance the interests of their shutdown-weary states and asserted their own political independence.

"I probably will have retribution in my state," Murkowski said. "That’s fine. That doesn’t bother me at all. If there is backlash, hey, that’s what goes on in D.C., but in the meantime there is a government that is shut down. There are people who are really hurting."

Two powerful women on the Democratic side of the aisle — Sens. Barbara A. Mikulski of Maryland and Patty Murray of Washington — took a hard line and pressed their Republican counterparts to temper their demands, but they also offered crucial points of compromise.

Together, the five senators starkly showed off the increasing power of women — even those who are not on the relevant committees — as their numbers grow in the upper chamber. Of the 13 senators on a bipartisan committee who worked on the deal framework, about half were women, even though women make up only 20 percent of the Senate. Sen. John McCain of Arizona joked at several points in their meetings, "The women are taking over."

Sen. Joe Manchin III, Collins’ first Democratic collaborator, said: "That gender mix was great. It helped tremendously." He added: "Would it have worked as well if it had been 12 women or 12 men? I can’t say for sure, but it worked pretty well with what we had."

The women are hardly in lock step politically. But their practice of meeting regularly and working on smaller bills together, even in a highly polarized Congress, set the stage for more significant legislation. Ayotte and Sen. Jeanne Shaheen, D-N.H., hosted an informal get-together for women in the Senate on Oct. 7.

"I don’t think it’s a coincidence that women were so heavily involved in trying to end this stalemate," Collins said. "Although we span the ideological spectrum, we are used to working together in a collaborative way."

More than two weeks into a government shutdown, Washington is now two short days from a possible default on federal obligations. The women showed pragmatism as negotiators in the midst of fierce partisanship and a level of frustration with the leaders of both parties that reflect their constituents and the nation.

"Where we find ourselves right now is unacceptable for America," Ayotte said. "It’s unacceptable as leaders that have been elected by the people of this country. We owe it to our constituents to resolve this now."

The Republican women involved in the compromise represented three of their party’s four female members. (Sen. Deb Fischer of Nebraska did not participate.) The bipartisan negotiating group included three Democratic senators as well, Amy Klobuchar of Minnesota, Heidi Heitkamp of North Dakota and Shaheen. The strongest Democratic voices counseling a hard line were also women.

Murray is chairwoman of the Budget Committee and would have primary responsibility for turning any broad agreement into a detailed plan for tax and spending policy over the next decade. Mikulski, who leads the powerful Appropriations Committee, has been the most forceful voice in efforts to blunt the impact of future budget cuts.

"Patty and I were emailing all weekend," Collins said. "I was not off the phone for longer than 20 minutes yesterday."

It was Murray who suggested language ordering an immediate start to budget talks. That language tempered Democratic concerns that the emerging deal would lock in across-the-board spending cuts for next year.

In contrast, Mikulski’s Republican counterpart on the Appropriations Committee, Sen. Richard C. Shelby of Alabama, and the ranking Republican on the Budget Committee, Sen. Jeff Sessions of Alabama, were notably absent from the talks. Rep. Paul D. Ryan of Wisconsin, chairman of the House Budget Committee, complained over the weekend that the Collins negotiations had excluded House Republicans.

The leader of the Republican trio, Collins, has emerged as the most powerful moderate in the Senate, and like her fellow Mainer and now-retired Sen. Olympia J. Snowe, often shows her own flair for the dramatic — the only Republican vote on several high-profile Democratic bills and the must-have Republican.

Ayotte, best known in the Senate for her hawkish foreign policy associations with fellow Republican Sens. McCain and Lindsey Graham of South Carolina, is using the moment to pursue an issue she has mostly paid lip service to: finding money for a military with its wings clipped by automatic spending cuts.

Brimming with frustration, Ayotte went to the Senate floor this month to deliver what her own staff now calls "the reality check" speech. Members of her own party had embraced "an ill-conceived strategy" to tie further financing of the government to gutting the president’s health care law, she said. The government shut down, yet the health care law is moving forward.

"I would say to my Republican colleagues in the House and to some in this chamber, it’s time for a reality check," she said.

Murkowski has been nursing wounds since the Republican establishment abandoned her in the wake of her defeat by a Tea Party candidate in the 2010 primary. She won as a write-in candidate and has seized the chance to assert her independence.

"Politics be damned," she said Monday.

© 2013 The New York Times Company